I would probably handle this with an external field and a formula/calculation because you need to isolate a specific value from the table.

For example, you could use a hidden number field to count how many rows have a date matching today, then you can use a >0 rule in your gateway (just make sure the field is numeric).

=COUNTIF(MyTable.Date,TODAY())

The TODAY() function returns the current date value with no time portion, and by adding that into the COUNTIF you get a count of rows that match.

You could combine this with other formulas like an IF to get a true/false or something else if that helps make your conditions easier to understand, but the countif would be a good starting point.

Just make sure your hidden field is set to Save the value.

There's more you can or might need to do if it always has to be the last row and you need to enforce that or something, but hopefully this will get you going.

EDIT: I just wanted to note that this also works with read only fields that have the default date set to the current date. Although the value is technically tracked at submission, the form does get a value so the calculation still works.